Calculation of transport properties for SiO/sub 2/

Among insulators, silicon dioxide plays a major role in the solid-state technology. Especially in recent years, experimental and theoretical investigations have focused on microscopic properties of this material related with reliability problems. In this work, ab initio calculations of the full-band structure of SiO/sub 2/ have been worked out by means of two different techniques: Hartree-Fock (HF) and Density-Functional Theory (DFT). All the analysed systems are polymorphs of silica, characterised by an electronic density similar to that of amorphous SiO/sub 2/. Specifically, the /spl alpha/- and /spl beta/-quartz, and the /spl alpha/- and /spl beta/-cristobalite are addressed. As the aim is that of applying the results to the investigation of transport properties for a bulk material, accurate calculations of both valence and conduction band structures, and corresponding densities of states (DOS), have been carried out in this work.